Group days in Business Objects? -

i'm trying group startdatetime in business objects. data startdatetime coming cisco server. in format 7/15/2013 10:52 am. trying group these it's 7/1, 7/2, etc.

i need create dimension out of day grouping can represent count of events on each date. right doing:

=formatdate([query 1 (1)].[startdatetime];"dd") 

i've tried variations of this, nothing working. used above formula group hours, replaced "dd" "hh", not sure why formula different.

any ideas? thank you. it's appreciated.

what if try

=formatdate([query 1 (1)].[startdatetime];"dd/mm/yyyy")